Diaphragms used in most of the cone and dome loudspeaker in the present market are supported by means of a fold-ring (some including a centering tab), the fold-ring supports the diaphragm so that the diaphragm vibrates under the action of a electroacoustical driving force to output the sound, and the fold-ring and the diaphragm form an integral structure. Some fold-rings and diaphragms are made of same material, both being an integral structure; some fold-rings and diaphragms are made of different materials, both also being an integral structure by bonder means.
A lot of efforts are made on the diaphragm, fold-ring and material, as well as technologies in the art in order to obtain the better performance for the loudspeaker. However, the maturated product which is characteristic of the integral support structure is difficult to make a great breakthrough in the technical performance with the state of the art, in particular in the high-pitch and super-high-pitch field.
In the conventional ribbon loudspeaker, an aluminum ribbon diaphragm with thickness in the range of about 0.006-0.02 mm is generally used, which is constructed as corrugation to support and keep the vibration of the diaphragm. Although this loudspeaker is an excellent high-pitch unit, the corrugated aluminum ribbon diaphragm is susceptible to slack when it is operated by an electromagnetic force in long term and other strong external force. The diaphragm may become elongated and offset the center area of the magnetic clearance so as to generate distortion at work, the problem concerning the reliability and service life is hard to be resolved over a long time of period.
Recently a compound diaphragm of polyimide and aluminum foil has been used in the ribbon loudspeaker, and in a head of the ribbon diaphragm a metal spring in a waveform as a transition section of the support-structural member serves as the integral support structure, which improves the reliability and service life of the ribbon diaphragm in a certain extent, however the problem of stress concentration at a interface between the strip compound diaphragm and the waveform supporting-structural member is still difficult to be resolved since it is not perfect technically.
In the planar-film loudspeaker, the diaphragm is a compound plastic-aluminium-foil diaphragm, which is made of the film such as polyester and polyimide as the basic material by means of flexible circuit board technology. The planar-film diaphragm vibrates with the help of the elasticity generated by the plastic film between the retain ring around the planar-film diaphragm and the flexible circuit board. In order to ensure that the diaphragm vibrates with sufficient elasticity, the elastic retain ring of the planar-film diaphragm must have a predetermined width, which results in increasing the total area of the diaphragm of the planar-film loudspeaker. Recently, some of the planar-film loudspeakers available in the market are formed by polyimide as the basic material. This type product is tested after signal input, as a result, it is found that partial or entire diaphragm has permanent deformation. This means that the elasticity of the supporting ring of the diaphragm cannot sufficiently satisfy the requirement of the diaphragm vibration. As a result of the permanent deformation the diaphragm offsets the normal work area and produces distortion.
The above mentioned support structure of the three diaphragm has a common character that the support structure and the diaphragm are formed as an integral piece. This kind structure has a certain limitation in technology.